Open-source hardware wallets: who publishes the firmware

A hardware wallet is open source when its maker publishes the firmware, the code that holds your keys and signs, under a licence that lets anyone read it, build it and reuse it. The companion app does not count: Tangem’s app is open, but Tangem keeps the card firmware closed. The table above records each maker’s firmware, with the repository or statement behind it.

What counts as an open-source hardware wallet?

Three different things get called open source:

• Firmware source. The code on the device. This is what the table records.
• Hardware design. Some makers also publish schematics and board files. Trezor’s hardware repository is licensed under the GNU Affero General Public License v3 and the CERN Open Hardware Licence v2 (Strongly Reciprocal); Trezor’s summary is “Our software and hardware are open-source and public” (Trezor).
• Companion software. The desktop or phone app. It usually prepares and broadcasts transactions while the device protects the signing keys; architectures vary, and Bitkey’s 2-of-3 design also has a key in the app.

The licence matters too. The Open Source Initiative’s definition says an open-source licence “may not restrict the program from being used in a business” and may not require a fee for selling it. Code you can read but not freely reuse is source-available. COLDCARD is the example in our table: Coinkite says “The repository applies MIT terms plus the Commons Clause” (COLDCARD), and the Commons Clause’s own site says “it is best not to call Commons Clause software ‘open source’” (commonsclause.com). Anyone can still read and build COLDCARD’s firmware; the restriction is on selling it.

Which hardware wallets have open-source firmware?

Published under an open-source licence: the five Trezor models (trezor-firmware), OneKey Pro, Blockstream Jade Plus and KeepKey.

Partly open (“Partial” in the table):

• BitBox02 Nova Multi: BitBox’s line is “Hide nothing by open sourcing everything, including the firmware on the BitBox” (BitBox), and the main firmware is public under Apache 2.0. The Nova’s Bluetooth chip firmware is public too, but builds on a Renesas SDK that, BitBox’s repository says, “cannot be redistributed here”.

• Passport Prime: Foundation publishes KeyOS, but the repository includes Microchip’s CryptoAuthLib under a licence that allows use “exclusively with Microchip products”.

• Ledger (Nano S Plus, Nano X, Nano Gen5, Flex, Stax): apps, SDK and libraries are public, the secure element OS is not. Ledger Academy says “Ledger’s operating system is partially reviewable and verifiable” and that “Ledger Wallet code is completely open-source” (Ledger).

• Keystone 3 Pro: Keystone calls its firmware “fully open source”, and the repository is public, but its README says one chip library (MH1903) is supplied as a library “rather than source code” because of intellectual-property restrictions.

• Bitkey: firmware published, except a third-party fingerprint sensor’s “proprietary matching algorithm”; the repository also says “we’re not ready to support external parties in building all Bitkey components.”

• SafePal S1 Pro and X1: for the S1 Pro, SafePal says “Essential aspects of the code for private key generation and other important features are open source”; for the X1, that “Relevant parts of the major code for the X1 have already been made open-source in stages” (SafePal). Neither says the whole firmware is published.

• COLDCARD Mk5 and Q: all published, but source-available rather than open source (above).

Closed: the Tangem Wallet and Tangem Ring, where Tangem argues “Revealing the source code would expose its hardware wallets to vulnerabilities” and points to audits instead (Kudelski Security in August 2018, then Riscure, per Tangem), and the ELLIPAL Titan 2.0. ELLIPAL wrote in December 2019 that it “chooses to be closed-source but remains the important parts open-source for users to verify our security”.

Not documented: Arculus (no statement found) and the NGRAVE ZERO, whose FAQ says the firmware “will be gradually open sourced except the secure element and secure operating system”; we found no published ZERO firmware.

Why is the secure element part often closed?

Secure element chips come with vendor terms. Ledger’s developer documentation describes “firmware that is under NDA and therefore closed source” next to “SDK and application-loaded code that is open-source friendly” (Ledger). In May 2023, in a message about Ledger Recover, Ledger’s CEO wrote that the company would “accelerate the open sourcing roadmap” (Ledger).

Trezor chose chips with fewer restrictions. Its Safe models use the OPTIGA Trust M secure element, which Trezor says it can use “without requiring Non-Disclosure Agreements (NDA)” (Trezor), and the Safe 7 adds the TROPIC01 chip, which “combines open architecture with advanced cryptography” (Trezor). An open architecture is not immunity: in June 2026 Trezor responded to a published attack on TROPIC01, saying “a full firmware fix cannot be applied remotely” because the attack targets hardware, and that “Compromising TROPIC01 alone is not enough to give access to the PIN”.

Can you check that the firmware on your device matches the source?

Partly, if the build is reproducible: you compile the published source and compare the result with the maker’s released firmware, following the maker’s rules for the signature and other data it excludes (Trezor notes local builds are not “bit-by-bit identical” because official images are signed). Checking which firmware is installed on your own device is a further step: BitBox, for example, says its bootloader “can also display the hash of the firmware before running it” (BitBox). Makers that document reproducible builds:

• Trezor: “you should be able to build the firmware and verify that it’s identical to the official firmware” (Trezor docs).
• BitBox: a guide to check that “your compiled firmware matches our published binaries”.
• COLDCARD: “build a release from source, and compare the result with the published firmware binary” (COLDCARD).
• Blockstream Jade: instructions to “verify the firmware offered by Blockstream is indeed built from the publicly available tagged source code”.
• Keystone: users can “compile it independently, and verify it against the officially released firmware using SHA256 hash comparison” (Keystone).
• OneKey: a help page with a video on reproducing a release.
• Passport Prime, with limits: Foundation’s notes say an encrypted part of the build means “third parties cannot reproduce it byte-for-byte”, and that external verifiers must obtain the release binaries from Foundation because “the release repository is not publicly readable”.

Without a reproducible build, published code tells you what the maker says it ships, not what is on your device.

Does open source make a hardware wallet safer?

Makers disagree, and both sides have a point. BitBox: “All our software code is public: everyone can check how the device operates and how secrets are handled” (BitBox). Ledger’s CTO, writing in August 2026: “Closed source does not mean unaudited: our code goes through regular evaluation by multiple independent vendors” (Ledger).

The record cuts both ways:

• Public code can still ship a serious bug. COLDCARD’s security status page says “In the July 2026 incident, a COLDCARD firmware bug weakened seed generation”, that attackers stole funds by regenerating keys offline, and that “Updating firmware does not repair an existing affected seed.”
• Outside researchers do find and report bugs in open firmware. BitBox’s July 2026 security update credits an external researcher and lists the fixes.
• Audits cover what was tested, when. Tangem’s card firmware passed earlier audits; in July 2026 Ledger’s Donjon lab published a laser fault attack on Tangem cards, disclosed to Tangem on 10 February 2026, which “requires physical access to the Tangem card”.

So open source is a property you can check, not a security rating. It lets anyone read the code and, with a reproducible build, compare it with a released binary; confirming what runs on a particular device takes a device-side check as well. Whether anyone has reviewed it well is a separate question; the datasheets list each device’s dated incidents. See also Is Ledger safe? and COLDCARD vs Trezor.

What we could not verify

• Arculus: no statement on whether the firmware source is published.
• NGRAVE: whether any ZERO firmware has been published since the FAQ’s promise (updated July 2023).
• SafePal: which parts of the S1 Pro and X1 firmware are published.
• Secure element internals: for Trezor’s OPTIGA chip and the other makers’ secure elements, we did not establish whether the chip’s own internal software is published.
• Reproducible builds for KeepKey, SafePal and Bitkey: we found no maker guide.